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Subject: Re: [hwloc-devel] Something lighter-weight than XML?
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2011-09-01 12:01:05

On Sep 1, 2011, at 11:49 AM, Brice Goglin wrote:

> Did you actually find many machines/distribs that don't have libxml2 installed by default? There are literaly hundreds of packages that depend on libxml2 (at least in Debian) so I am not sure depending on it is really a problem.

Cray, for sure. Josh told me off-list that it's a real PITA for them to build/support libxml on the ORNL Crays.

Blue Gene? Windows?

> Also are there really some string space problems?

No. The space savings is a minor benefit; I only included it for completeness.

> Otherwise, implementing this is likely easy, especially if you find somebody to do it :) Start from the XML export, convert it into a text export, and write the corresponding import (starting from the XML import may be hard because it's recursive).
> Would you need an export to a file or to a memory buffer or both?

Memory buffer would be most preferable, because we're going to generate it on the back end node, pack it to a network buffer, send it, receive it on the head node, unpack it from the network buffer, and slurp it into a hwloc topology.

> Last but not least: what's the deadline?

Ralph is actively working on code for the RFC I sent around yesterday:

We'll probably use XML just to get it going, but it would be good to not equate "libxmpi" with "hwloc" in OMPI developers' brains. :-) So -- "sometime soon" would be nice.

I could *probably* write this, but I'm guessing you guys could write it much faster than I could...

Jeff Squyres
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